116 строки
3.1 KiB
C
116 строки
3.1 KiB
C
/* Redirect. Simple mapping which alters dst to a local IP address. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/ip.h>
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#include <linux/timer.h>
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/netdevice.h>
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#include <linux/if.h>
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#include <linux/inetdevice.h>
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#include <net/protocol.h>
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#include <net/checksum.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/netfilter/nf_nat_rule.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
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/* FIXME: Take multiple ranges --RR */
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static bool
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redirect_tg_check(const char *tablename, const void *e,
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const struct xt_target *target, void *targinfo,
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unsigned int hook_mask)
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{
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const struct nf_nat_multi_range_compat *mr = targinfo;
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if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
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pr_debug("redirect_check: bad MAP_IPS.\n");
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return false;
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}
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if (mr->rangesize != 1) {
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pr_debug("redirect_check: bad rangesize %u.\n", mr->rangesize);
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return false;
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}
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return true;
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}
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static unsigned int
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redirect_tg(struct sk_buff *skb, const struct net_device *in,
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const struct net_device *out, unsigned int hooknum,
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const struct xt_target *target, const void *targinfo)
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{
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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__be32 newdst;
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const struct nf_nat_multi_range_compat *mr = targinfo;
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struct nf_nat_range newrange;
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NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING
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|| hooknum == NF_INET_LOCAL_OUT);
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ct = nf_ct_get(skb, &ctinfo);
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NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
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/* Local packets: make them go to loopback */
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if (hooknum == NF_INET_LOCAL_OUT)
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newdst = htonl(0x7F000001);
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else {
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struct in_device *indev;
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struct in_ifaddr *ifa;
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newdst = 0;
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rcu_read_lock();
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indev = __in_dev_get_rcu(skb->dev);
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if (indev && (ifa = indev->ifa_list))
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newdst = ifa->ifa_local;
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rcu_read_unlock();
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if (!newdst)
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return NF_DROP;
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}
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/* Transfer from original range. */
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newrange = ((struct nf_nat_range)
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{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
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newdst, newdst,
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mr->range[0].min, mr->range[0].max });
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/* Hand modified range to generic setup. */
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return nf_nat_setup_info(ct, &newrange, IP_NAT_MANIP_DST);
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}
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static struct xt_target redirect_tg_reg __read_mostly = {
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.name = "REDIRECT",
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.family = AF_INET,
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.target = redirect_tg,
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.targetsize = sizeof(struct nf_nat_multi_range_compat),
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.table = "nat",
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.hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
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.checkentry = redirect_tg_check,
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.me = THIS_MODULE,
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};
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static int __init redirect_tg_init(void)
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{
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return xt_register_target(&redirect_tg_reg);
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}
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static void __exit redirect_tg_exit(void)
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{
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xt_unregister_target(&redirect_tg_reg);
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}
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module_init(redirect_tg_init);
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module_exit(redirect_tg_exit);
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